Plasticfruits, part 5: the case of Dioscorea (Dioscoreaceae)

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The herbaceous genus Dioscorea ( and contains more than 600 spp.

It occurs on all vegetated continents, and many islands (please scroll to map in

There is significant variation in the vegetative features. For example:

However, the variation in the fruits of Dioscorea is extreme (

Many spp. are 'doubly-adapted for dispersal by wind, by virtue of wings on both the fruits and the seeds; by contrast, a few are so clearly adapted for dispersal in the gastrointestinal tracts of birds that they were formerly assumed to constitute a separate genus (Tamus).


A clade of spp. in Brazil, in which the plants are short, has round, wingless capsules ( and and

Most of the sections and spp. of Dioscorea bear winged, dehiscent capsules, containing seeds that

The following show the winged, dehiscent capsules in various spp. in Australia, Asia, and North America:

Also please see and


One section (Rajania, restricted to the Caribbean islands) has samaras ( and and and instead of capsules ( and


Most relevant for this Post, one 'infragenus', namely Tamus, has succulent, bright-hued fruits (, and several other clades within Dioscorea also have fleshy fruits, or fruits intermediate between dehiscent capsules and fleshy fruits (e.g. Dioscorea ovinala and Dioscorea anataly of Madagascar, and

The best-known examples are Dioscorea communis ( and Dioscorea orientalis (, which occur in the Canary Islands and Madeira (, Europe, the Maghreb, the Caucasus, and the Levant.

It is remarkable enough that a single genus stretches from samaras (with specialised dispersal of the diaspore by wind) to fleshy fruits (with specialised dispersal and sowing by birds).

However, what is particularly remarkable is that the variation in fruit-form cuts across the clades within the genus. This suggests that variation in fruit-form has arisen independently, in the evolutionary process, repeatedly within Dioscorea.

Dioscorea communis and D. orientalis, bearing red berries attractive to seed-dispersing birds, are most closely related to section Borderea, in which the fruits are capsules, containing seeds that lack wings ( and see Fig. 2a, on page 190, in


In summary, fleshy fruits within Dioscorea are clearly-defined morphologically and adaptively, but poorly-defined phylogenetically. This further exemplifies the evolutionary plasticity of fruits within genera worldwide - which is the focus of this series of Posts.


Dioscorea communis:

Dioscorea orientalis:

Publicado el julio 13, 2023 03:21 MAÑANA por milewski milewski


Publicado por milewski hace casi 1 año
Publicado por milewski hace 12 meses

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